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Any reason I can't or shouldn't run same size tires front and rear? by Napoleon_Tanerite
Started on: 09-22-2015 10:39 PM
Replies: 24 (723 views)
Last post by: Patrick on 10-02-2015 12:49 PM
Napoleon_Tanerite
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Report this Post09-22-2015 10:39 PM Click Here to See the Profile for Napoleon_TaneriteSend a Private Message to Napoleon_TaneriteEdit/Delete MessageReply w/QuoteDirect Link to This Post
I'm shopping wheels/tires for my 87. I know most guys run narrower front tires on Fieros, but how big of a difference does it make? I'm planning on running Autocross with the car and using Bridgestone Potenza RE-71R tires. I've had great success with these in my GTO, and would put them on the Fiero in a heart beat. The problem is they are directional, and given the wear induced during autocross, they will need to be rotated frequently. On the GTO I rotate the front and rear tires, keeping them on the same side (LF becomes LR, and so on). I'm thinking of doing 225x45R17 on all four corners. Does anyone have a potential problem I should consider?
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Report this Post09-22-2015 10:43 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
Wider tires up front means more resistance against change in direction, so you might find yourself with a slightly slower time, even though you've got "better" tires.
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Napoleon_Tanerite
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Report this Post09-22-2015 10:47 PM Click Here to See the Profile for Napoleon_TaneriteSend a Private Message to Napoleon_TaneriteEdit/Delete MessageReply w/QuoteDirect Link to This Post
I considered that, but the rotation problem has me stuck. The only option for rotation with staggered tires is a dismount/remount on the opposite wheel, and they're still running in the front where the majority of wear takes place.
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sardonyx247
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Report this Post09-22-2015 11:06 PM Click Here to See the Profile for sardonyx247Click Here to visit sardonyx247's HomePageClick Here to Email sardonyx247Send a Private Message to sardonyx247Edit/Delete MessageReply w/QuoteDirect Link to This Post
Running the same size up front will make it plow less.
I like it myself, the less plowing that is.
GM did it to shift the center of gravity forward a bit, and understeering is safer. Thus a win win for GM, not the best for GOOD drivers.
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Napoleon_Tanerite
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Report this Post09-22-2015 11:30 PM Click Here to See the Profile for Napoleon_TaneriteSend a Private Message to Napoleon_TaneriteEdit/Delete MessageReply w/QuoteDirect Link to This Post
I've been driving overpowered RWD cars all my life. I ain't skeert of oversteer.
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Jake_Dragon
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Report this Post09-23-2015 03:33 AM Click Here to See the Profile for Jake_DragonSend a Private Message to Jake_DragonEdit/Delete MessageReply w/QuoteDirect Link to This Post
I run 15/215 on all 4 corners have for years. That way I can rotate the tires.
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Patrick
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Report this Post09-23-2015 03:50 AM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Napoleon_Tanerite:

I'm planning on running Autocross with the car... I'm thinking of doing 225x45R17 on all four corners.


I run 225/50/16 on all four corners of my Formula when I'm autocrossing... and they're not directional, so I have plenty of options for rotating the tires.

My street tires are 225/50/16 in the rear and 205/55/16 in the front. To be honest, I much prefer the feel of the car with this tire size combination on the car.

When I eventually buy my next tires for autocross, I may re-evaluate my tire choices and not use all the same size tires again.

[This message has been edited by Patrick (edited 09-24-2015).]

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hnthomps
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Report this Post09-23-2015 10:21 AM Click Here to See the Profile for hnthompsClick Here to Email hnthompsSend a Private Message to hnthompsEdit/Delete MessageReply w/QuoteDirect Link to This Post
i run 265 x 50 x 15 on all four corners on my Meras and it works out well. The only issue is the turning effort for the front wheels is increased at low speeds.

Nelson
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Report this Post09-25-2015 12:59 AM Click Here to See the Profile for jscott1Send a Private Message to jscott1Edit/Delete MessageReply w/QuoteDirect Link to This Post
Rotating tires is overrated in my opinion. You might squeeze a few more miles out of them by rotating, but I've been driving cars with different size front/rear for decades and just gave up worrying about it.

If the fronts wear out first so what? Just replace them. But stay away from Discount Tire...they insist on putting the new tires on the back, no matter what. They are morons and I argued with them until I was blue in the face to put the new tires on the front and finally just left and went to NTB instead.

[This message has been edited by jscott1 (edited 09-25-2015).]

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Jake_Dragon
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Report this Post09-25-2015 05:24 AM Click Here to See the Profile for Jake_DragonSend a Private Message to Jake_DragonEdit/Delete MessageReply w/QuoteDirect Link to This Post
The rear tires wear out a lot faster than the front tires on my car So I rotate the fronts to the back then when its time replace the fronts and start over.
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Report this Post09-25-2015 08:21 AM Click Here to See the Profile for fierofoolClick Here to visit fierofool's HomePageClick Here to Email fierofoolSend a Private Message to fierofoolEdit/Delete MessageReply w/QuoteDirect Link to This Post
Think about the construction of the Fiero. Underneath a decorative skin is the same skeleton. Either with or without ground effects is the basic difference. All those cars without ground effects, except the Formula run same size tires front and rear. Only the notchback models with ground effects have same size. So, apples to apples, the 86 and 87 GT and SE are the same cars with different skins. The SE has same size tires front and rear, the GT has staggered tires. I think, in part, staggered sizes on the GT are aesthetic.

At the same time, the rear of the 86-88 GT has more than a hundred pounds extra weight as opposed to the notchbacks. Larger tires support that weight better, and also raise the rear end of the car. Raising the rear will have the effect of reducing understeer. Go too large and you get serious oversteer and the rear will want to come around on the slightest turn or maneuver.

The fastbacks tend to wear the rear tires faster than front tires. If you're running a fastback, it might help to balance the tire wear, whether on the course or highway.
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Report this Post09-25-2015 08:52 AM Click Here to See the Profile for jaskispyderSend a Private Message to jaskispyderEdit/Delete MessageReply w/QuoteDirect Link to This Post
I am guessing they follow this (below). I can tell you from personal experience, I have had newer tires on front and worn on the rear and the rear would swing around (FWD) in the snow. Very dangerous. I have gotten to the point that I don't run "worn" tires in the winter because of this.... it is a no-win situation.
http://www.tirerack.com/tir...chpage.jsp?techid=52

"When tires are replaced in pairs in situations like these, the new tires should always be installed on the rear axle and the partially worn tires moved to the front. New tires on the rear axle help the driver more easily maintain control on wet roads since deeper treaded tires are better at resisting hydroplaning.

Hydroplaning occurs when the tire cannot process enough water through its tread design to maintain effective contact with the road. In moderate to heavy rain, water can pool up in road ruts, depressions and pockets adjacent to pavement expansion joints. At higher speeds, the standing water often found in these pools challenges a tire's ability to resist hydroplaning.

Exactly when hydroplaning occurs is the result of a combination of elements including water depth, vehicle weight and speed, as well as tire size, air pressure, tread design and tread depth. A lightweight vehicle with wide, worn, underinflated tires in a heavy downpour will hydroplane at lower speeds than a heavyweight vehicle equipped with new, narrow, properly inflated tires in drizzling rain.

If the front tires have significantly less tread depth than the rear tires, the front tires will begin to hydroplane and lose traction on wet roads before the rear tires. While this will cause the vehicle to understeer (the vehicle wants to continue driving straight ahead), understeer is relatively easy to control because releasing the gas pedal will slow the vehicle and help the driver maintain control.

However, if the front tires have significantly more tread depth than the rear tires, the rear tires will begin to hydroplane and lose traction on wet roads before the fronts. This will cause the vehicle to oversteer (the vehicle will want to spin). Oversteer is far more difficult to control and in addition to the initial distress felt when the rear of the car starts sliding, quickly releasing the gas pedal in an attempt to slow down may actually make it more difficult for the driver to regain control, possibly causing a complete spinout."

 
quote
Originally posted by jscott1:

If the fronts wear out first so what? Just replace them. But stay away from Discount Tire...they insist on putting the new tires on the back, no matter what. They are morons and I argued with them until I was blue in the face to put the new tires on the front and finally just left and went to NTB instead.



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Napoleon_Tanerite
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Report this Post09-25-2015 10:32 AM Click Here to See the Profile for Napoleon_TaneriteSend a Private Message to Napoleon_TaneriteEdit/Delete MessageReply w/QuoteDirect Link to This Post
Based on my experience with the GTO, front tires wear a LOT faster than rear during autocross. I ran ONE weekend on new tires with the GTO. The rears looked new, and the fronts already have me worried they won't last another couple of events. I know the GTO is a lot more front heavy, but with a car like that you'd think the rears would go first.
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Report this Post09-25-2015 09:54 PM Click Here to See the Profile for jscott1Send a Private Message to jscott1Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by jaskispyder:

I am guessing they follow this (below).



That's all well and good, but if you have different sized tires front and back and the fronts wear out first for some reason you have to replace all 4. Screw that I'll deal with the oversteer.
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Report this Post09-26-2015 08:16 PM Click Here to See the Profile for rogergarrisonClick Here to Email rogergarrisonSend a Private Message to rogergarrisonEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Napoleon_Tanerite:

I've been driving overpowered RWD cars all my life. I ain't skeert of oversteer.


SOOOOO true. I love it too

. I NEVER rotate tires anyway. When I do need tires, I usually only need to buy 2 instead of 4. Wider tires on front wear faster. Unless I do burnouts, my front tires normally wear out twice as fast as the rears. Not a big deal since its normal for me to get 100,000 miles out of a set of decent tires. I prefer Dunlop and Bridgestone. Ive also had really good luck with Continentals. Original Contis were on my Sebring I drove for 10 years/ 104,000 miles. Still had at least 50% of orig tread. I keep all my tires at around 40 pnds so they wear evenly across the treads...no worn off shoulders or centers. When you pick tires, get ones that the tread width equals the rim width. Dont put 10" wide tires on a 6" rim.

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Report this Post09-27-2015 01:24 PM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
Just a guess but GM may have designed the Fiero with a specific tire track width that needed narrower front tires to achieve the same tire track width that is in the rear.
So the question is, If you put wider tires on the front does it unbalance the track width, affect steer and/or require a new alignment?

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Report this Post09-27-2015 01:26 PM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post

Dennis LaGrua

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...

[This message has been edited by Dennis LaGrua (edited 09-27-2015).]

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Report this Post09-27-2015 01:51 PM Click Here to See the Profile for dobeySend a Private Message to dobeyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Dennis LaGrua:

Just a guess but GM may have designed the Fiero with a specific tire track width that needed narrower front tires to achieve the same tire track width that is in the rear.
So the question is, If you put wider tires on the front does it unbalance the track width, affect steer and/or require a new alignment?



As long as you don't change the offset of the wheels, wouldn't the track width be the same with 205 or 225 in the front? The center of the wheel/tire doesn't change with wider tires.
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Napoleon_Tanerite
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Report this Post09-27-2015 01:57 PM Click Here to See the Profile for Napoleon_TaneriteSend a Private Message to Napoleon_TaneriteEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by rogergarrison:


SOOOOO true. I love it too

. I NEVER rotate tires anyway. When I do need tires, I usually only need to buy 2 instead of 4. Wider tires on front wear faster. Unless I do burnouts, my front tires normally wear out twice as fast as the rears. Not a big deal since its normal for me to get 100,000 miles out of a set of decent tires. I prefer Dunlop and Bridgestone. Ive also had really good luck with Continentals. Original Contis were on my Sebring I drove for 10 years/ 104,000 miles. Still had at least 50% of orig tread. I keep all my tires at around 40 pnds so they wear evenly across the treads...no worn off shoulders or centers. When you pick tires, get ones that the tread width equals the rim width. Dont put 10" wide tires on a 6" rim.




I plan on running Bridgestone Potenze RE-71Rs on the car. I'll be surprised if I get 10k miles out of them. I've got a daily, and neither of my Pontiacs are it.
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Report this Post09-28-2015 03:36 PM Click Here to See the Profile for rogergarrisonClick Here to Email rogergarrisonSend a Private Message to rogergarrisonEdit/Delete MessageReply w/QuoteDirect Link to This Post
Of course mileage is affected pretty radically if you use soft performance type tires. I had a Shelby Mustang with Eagle GTs that only got 15,000 tops. I was on the 3rd set when I sold it at 40,000 miles. Those and Goodrich are great for traction, but way to soft for my liking in a street tire.
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Report this Post09-28-2015 07:23 PM Click Here to See the Profile for jaskispyderSend a Private Message to jaskispyderEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by jscott1:


That's all well and good, but if you have different sized tires front and back and the fronts wear out first for some reason you have to replace all 4. Screw that I'll deal with the oversteer.


Not practical in the land of ice and snow
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Report this Post09-30-2015 04:46 PM Click Here to See the Profile for rogergarrisonClick Here to Email rogergarrisonSend a Private Message to rogergarrisonEdit/Delete MessageReply w/QuoteDirect Link to This Post
I agree with you Jscott. I want my best tires on front...dont care what 'experts' say. I want it to turn when I want to turn. I know how to drive RWD cars and the oversteer is just fine with me. When I turn a corner in the snow, i want the front to turn first, I dont care what the rear does because I can control that, even sideways. All I need is enough tread on the rear for traction enough to get going. With best tread in the rear and your trying to turn, they will push the car straight no matter where you turn the fronts. In braking, 90% of that happens at the front. Ive had cars I even disconnected rear brakes till I could fix them and barely noticed so I want the good tread on the stopping tires. You cant disconnect front though, rears alone barely will slow you down.

[This message has been edited by rogergarrison (edited 09-30-2015).]

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Report this Post10-01-2015 06:32 PM Click Here to See the Profile for BruceClick Here to Email BruceSend a Private Message to BruceEdit/Delete MessageReply w/QuoteDirect Link to This Post
So, what would be the better selection to run on all 4 wheels: 205 or 215 (60 /15)?
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Report this Post10-02-2015 09:32 AM Click Here to See the Profile for Kevin87FieroGTSend a Private Message to Kevin87FieroGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
215/60-15 on all 4 work nice on the GT. Wear after 10,000 mi all even. No problem with steering effort. Very good handling and ride characteristics.

[This message has been edited by Kevin87FieroGT (edited 10-02-2015).]

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Report this Post10-02-2015 12:49 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by rogergarrison:

I want my best tires on front...


Uh oh, I agree with Roger on this one.
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